Known door latch mechanisms include the traditional rotary type where a door knob is rotated to unlatch a latch bolt, and so-called push-pull types in which a door handle is either pushed or pulled to retract the latch bolt. The push-pull type of door latch mechanisms are particularly suited to high traffic or sanitary environments, such as public restrooms, hospitals, clinics or the like, where it is desirable to unlatch the latch bolt without using ones hands.
It is well known that various infectious diseases are spread through contact with a contaminated surface such as a door handle or similar frequently contacted surface. Thus, it would be particularly advantageous to be able to open a door after washing ones hands without having to use ones hands because touching the door handle partially negates the beneficial effect of hand washing. The demand for such a device is particularly acute in facilities open to the general public such as in commercial or institutional settings.
Particularly in the case of hospitals, clinics, rehabilitation centers, nursing homes and similar facilities, it is further desirable to equip such a door latch mechanism with an integral locking mechanism including a lock override. Notably, it is desirable to temper the desire for privacy with the somewhat conflicting need to provide access to the occupant in the event of an emergency. Thus, what is truly required is a lock which prevents accidental intrusion while facilitating reasonable ease in overriding the lock in the event of an emergency.
One such door latch mechanism is disclosed in U.S. Pat. No. 5,403,047 which patent is hereby incorporated by reference. In the '047 patent, locking is obtained by interference with the push/pull action of the door handle. However, the door latch mechanism disclosed in the '047 patent contains several disadvantages. One disadvantage relates to the complexity of the door locking mechanism and the large number of parts required.
Consequentially, a first object of the present invention is to provide an improved push-pull latch mechanism including a latch mechanism and an override switch which utilizes a relatively simple construction.
A second object of the invention is to provide an improved push-pull latch mechanism which provides a more robust construction.
A third object of the invention is to provide an improved push-pull latch mechanism having component parts configured to facilitate interchangeability.
A fourth object of the invention is to provide an improved push-pull latch mechanism including a lock knob configured to be located on either interior or exterior sides of the door by merely interchanging the latch covers.